COMPETENCE 7 (15)

126問 • 2年前

問題一覧

1. Moisture accumulating in electric motors and generator windings having a cold insulation resistance greater than 50,000 ohms may be baked out with internal heat. This heat can be developed by_

feeding current into the windings at low voltage

2. What precaution should be taken with a vessel's impressed current cathodic protection system after a drydocking period during which the hull has been painted?

The unit should remain off for the specified amount of time so as not to disturb curing

3. The schematic symbol for an operational amplifier in an analogue circuit is a

Triangle

4. A three-phase squirrel-cage induction motor will run hot due to

Open stator coils

5. A capacitor can be tested using a megohmmeter or an ohmmeter, if the meter is connected to a shorted capacitor, the meter pointer should_

immediately deflect to and remain at zero

7. A switchboard for an AC electrical system requires the use of which of the following devices?

Frequency meter

8. When changing tubular fuses always use a

Fuse puller

9. The greatest single cause of electrical failure is

The breakdown of insulation

10. What will you do if the generator is exposed to rain or any water?

Make a megger test

11. A safety device in an electrical circuit consisting of metal strip that melts when the current exceeds the safe level is called

fuse

12. An electric tachometer receives the engine speed signal from?

bimetallic sensing device

13. A current at which a magnetic-type overload relay tends to trip maybe decreased by raising the plunger further into the magnetic circuit of the relay. This action will

Increases magnetic pull on the plunger and requires less current to trip the relay.

14. What does the variable resistance placed in the rotor circuit of a wound-rotor induction motor provide?

speed control

15. Periodic testing of circuit breaker is necessary to assure that a correct rated and properly installed unit

will continue to provide the original degree of protection

16. Which of the following materials is recommended for finishing the slip rings after grinding or turning?

crocus cloth

17. What kind of device that has two pieces of metal joined together so that when its junction is heated, a voltage is produced?

Thermocouple

18. When removing ball or roller bearings from the shaft of a motor, you should use a

wheel puller

19. What do do you call on a periodic testing by a shore side support technician using a special camera which can detect potentially dangerous loose or corroded bus bar and controller connections?

heat sensitive thermography

20. When the equivalent circuit diagram of double squirrel-cage induction motor is constructed the two cages can be considered.

in parallel

21. What motor is fitted with an instantaneous overload relay?

Winch

22. If both the "high level and "low level''alarms come on for the same address of a centralized control console, the most likely problem is alan

sensor failure

23. Which of the listed procedures should be carried out to prevent moisture damage to electrical apparatus during extended periods of idleness?

Place heat lamps in the motor housings.

24. A common type of protective covering used on electrical conductors is

fibrous braid

25. When a nickel-cadmium battery begins gassing while connected to the battery charging circuit, you should

do nothing as this is a normal condition when charging

26. A molded-case breaker provides protection against short circuits by using ?

electromagnet

27. What may happen to the components of a winch master control switch, if the cover gasket becomes deteriorated?

Rapid corrosion of switch components.

28. What should you use to determine if a stator coil is grounded?

megger

29. The charging of lead-acid storage batteries will always result in ?

a dangerously explosive gas being liberated

30. With both ends of a three conductor cable disconnected and arranged without the conductors touching each other, an ohmmeter reading of 'zero' ohms between the ends of one conductor would indicate

continuity

31. What is a device that changes an input signal of one type into an output signal of a differnt type that is proportional to the original input?

Transducer

32. What gives the information about the speed of a motor in D. C. Generator, ?

Speedometer

33. To check the three line fuses of three-phase system consisting of a three-phase motor, you must

make sure the motor is operating at full load to guard against a false reading

34. periodic testing of circuit breakersis necessary to assure that a correct rated and properly installed unit

will continue to provide the original degree of protection

35. How should controller contacts be routinely cleaned?

wiping with a clean dry cloth

36. Which of the following safest precautionary measure is to be done prior working on the motor of the cargo winch?

Switch off main switch and put sign do not switch on.

37. Four lamps are connected in parallel in a single circuit. If one of the lamp burns out, the others will

burn with their original intensities

38. Electrical leads and insulation on a motor should be painted with

insulating varnish

39. Which of the following physical characteristics does a wound-rotor induction motor possess that a squirrel-cage motor does not?

Slip rings

40. Why should you use a high impedance multimeter when troubleshooting electronic equipment?

so as not to load down the circuit and obtain erroneous voltage readings

41. Air gap readings should be periodically taken for electrical generation equipment. The best tool to use to take these measurement is a

tapered, long blade gage

42. Which test on a transformer provides information about the regulation, efficiency and heating under load condition?

Back to back test

43. It is a type of electrical fault that happens when a phase conductor is completely or partially interrupted:

Open circuit fault

44. The windings of electric generators during short idle periods should be

kept warm by using strip or space heaters

45. The part of the shipboard electrical system used to control the distribution of power to the branch circuits, is the

main switchboard

46. A temperature instrumentationsystem for an engine room console consistes of a resistance temperature detector(RTD), a measuring bridge circuit, and a meter(or alarm circuit). Which of the following statements is true concerning the measuring bridge circuit?

The resistance bridge is said to be balanced when its output voltage is zero

47. In the event of a power failure during cargo loading operations, which of the following can stop the movement of an electric powered cargo winch?

A spring set brake

48. A device which can be used to check the calibration of a circuit breaker is a

portable low voltage high current testing unit

49. Before reassembling any machinery, what should you do?

clean any corroded surfaces and file all burrs smooth

50. Air gap readings should be periodically taken for electrical generation equipment. The best tool to use to take these measurements is a

tapered, long blade gage

51. A semiconductor that decreases in resistance with an increase in temperature is known as?.

thermopile

52. What should be done to protect the rotor of a motor disassembled for maintenance or overhaul?

it must be supported by two "V" notched wood blocks

53. What is a variable-resistance component used as a control device in electrical circuit?

Potentiometer

54. What kind of electrical cable that is widely used and is highly resistant to mechanical damage?

Aluminum cable covered with insulation.

55. When trouble shooting electronic equipment, what is the first step to be taken before testing the circuit voltage?

check the voltage supply from the power source

56. The purpose of a main switchboard circuit breaker's reverse-power trip is to

prevent alternator motorization

57. Temporary repairs to an open DC propulsion armature coil can be made by

disconnecting coil ends, insulating each, and short circuiting the two commutator bars

58. When charging lead-acid batteries, you should reduce the charging rate as the battery nears its full charge capacity to

prevent excessive gassing and overheating

59. When shipboard electrical distribution circuits are connected in parallel, additional parallel circuits will cause the total circuit resistance to

decrease, causing an increase in the line current

60. What is a device that converts fluid powers into linear mechanical force and motion that consists of a movable piston, connecting rod, and plunger operating in a cylindrical cavity?

Cylinder

61. During maintenance of circuit breakers,

inspect for wear and misalignment of main contacts

62. What is used in most for starting three-phase induction motors of five (5) horsepower or less ?

across-the-line starters

63. Periodic testing of circuit breakers is necessary to assure that a correct rated and properly installed unit

will continue to provide the original degree of protection

64. You are testing the insulation in an AC generator with with a megohmeter. the resistance value of a dry, clean winding will_

continue to rise as the test potential is maintained, becoming fairly steady as the leakage current stabilizes

65. Which of the following data is required to draw the circle diagram for an induction motor?

Bolck rotor test, no load test and stator resistance test

66. The removal of paint from electrical equipment such as generators, should be cautiously undertaken because

the paint dust is composed of abrasive and semi-conducting materials which impair insulation

67. A reversible electric motor with worm gear that is connected to the flywheel to position engine parts is the

turning gear

68. If a small electric motor is immersed in salt water it should be I. washed in fresh water II. dried in an oven III. blow air until it dries

I only.

69. To carry out an insulation resistance test, one terminal of the megohmmeter should be connected to the winding, with the other terminal being connected to the

frame of the machine

70. Before working on an electric motor starter panel located on the main deck, what should you do FIRST?

Open the circuit breaker and tag out

71. A fuse the blows often should be replaced only with a fuse of __.

the recommended current and voltage rating

72. Electrical Insulating rubber gloves should be dielectrically tested every how many months?

6 months

73. It is a type of temperature sensor that has the characteristic of being very accurate, linear and has a good long term stability.

RTD'S

74. A self-excited DC generator fails to come up to its normal 440 volts. What could be the probable cause?

low armature speed

75. A common type of protective covering used on electrical conductors is,

Fibrous braid

76. The air gap provided in induction motors should be checked periodically with a feeler gage to detect an unequal air gap and

Mechanical damage to rotor

77. A temperature instrumentation system for an accomodation reefer room consists of a resistance temperature detector (RTD), a measuring bridge circuit and a meter or alarm circuit. Which of the following is true concering the measuring bridge circuit ?

The ressistance bridge is said to be balanced when its output voltage is zero

78. Electrically operated safety devices on auxiliary diesel engines functions to stop the engine by

shutting off fuel supply

79. A molded-case circuit breaker provides protection against short circuits by using alan ?

electromagnet

80. The proper way to apply plastic electrical tape to an electric cable splice is to

wind the tape so that each turn overlaps the turn before it

81. The division of kilowatt load between two paralleled alternators is determined by the ?.

load-speed characteristics of the governors

82. What is the result if the solenoid coil burns on a cargo winch with an electrical brake?

The brake will be set by spring force.

83. The air gap provided an induction motor should be checked periodically with a feeler gage to detect

any increase in rotor bearing wear

84. Encrusted dirt accumulated inside a motor should be removed with a

Fiber scraper

85. A temperature instrumentation system to an engine room console consists of a resistance temperature detector (RTD), a measuring bridge circuit , and a meter (or alarm circuit). Which of the following statements is true concerning the measuring bridge circuit?

The resistance bridge is said to be balanced when its output voltage is zero

86. When a replacing a fuse with one of a higher rating than the original, which of the following is true?

It endangers the apparatus it is supposed to protect

87. The purpose of a motor under voltage protection device is to

prevent high armature current when power is restored

88. The power scale of circle diagram of an induction motor can be found from

short-circuit test only.

89. What electrical apparatus can test insulating efficiency in an electric installation?

Megger tester

90. When reading electrical motor controller diagrams, it helps to know that

current paths in the power circuit are drawn as heavy lines and in control circuit as lighter lines

91. What devices is fitted to prevent the generator windings from absorbing moisture while at standstill?

Space heater

92. Any electric motor can be constructed to be?

explosion proof

93. A common type of protective covering used on electrical conductors is

rubber or plastic

94. Which of the following statements concerning the maintenance of solid-silver Contacts in relay and auxiliary control circuits is correct?

They should be filed with a fine-cut file when projections extend beyond the contact surface

95. What can you do if the generator is exposed to rain or any water?

Make a megger test

96. What is the cause when an alternator failed to produce line voltage?

exciter generator failure

97. Moisture as a result of condensation occurring inside of the cargo winch master switches, can be reduced by?

using strip heaters inside the switch box

98. Regulations require each motor controller to have a wiring diagram located

on the inside of the controller door

99. A device which can be used to check the calibration of a circuit breaker is a

portable low voltage high current testing unit

100. Which of the following statements concerning analog and digital devices are correct?

The variables in digital systems are fixed quantities and the variables in analog systems are continuous quantities.

100

101. When a megohmmeter is being used to test insulation resistance, current leakage along the surface of the insulation is indicated by the megohmmeter's pointer ?

kicking slightly down scale as voltage is applied

M#5 Section and Title v2

ユーザ名非公開 · 32問 · 13日前

M#5 Section and Title v2